EQUINE | Equine Disease Update
EQUINE | Equine Disease Update
Corneal Ulcers
Dr Antony Goodhead BSc , BVSc , MMedVet [ Ophth ], CertVetOphthal
Johannesburg Animal Eye Hospital
Corneal disease in the horse is a common problem facing a horse owner and the overseeing veterinarian . Eye disease is considered one of the most common reasons for a veterinarian to see a horse . Statistics show that about 9-11.5 % of all equine consultations are eye related whilst of ocular diagnoses , 57 % were corneal ulcers . A horse ’ s eyes are prominently located at the sides of the head and this may result in the high levels of ocular trauma . Frequently the physical status of the cornea will have a serious impact on the general status of the eye and frequently alert one to the presence of intraocular disease .
A corneal ulcer occurs when there is a break in the corneal epithelium . These lesions are usually easily identified owing to the presenting signs of lacrimation and blepharospasm . As part of the initial examination one needs to ensure there is no mechanical reason present for the erosion . Traumatic incidence is probably the most common cause in horses .
A superficial uncomplicated ulcer is acute in onset . It usually occurs as a result of a superficial abrasion and loss of the corneal epithelium without involvement of the deeper stroma . It stains fluorescein positive and generally has no cellular debris , malacia , stromal defects and less likely to be showing signs of uveitis . In all cases one should consider the ulcer to be potentially infected with bacteria and if the ulceration is a result of vegetable matter or where the ulcer persists in spite of long term antibiotic therapy then one should consider a fungal involvement . It is good practice to take a corneal culture [ fungal and bacterial ] of the lesion followed by scrapings for cytology . In order to ensure a good sample one may physically need to perform a scraping of the lesion . Topical ophthalmic anaesthetic drops can be applied and using the back of a scalpel blade / cytobrush the lesion can be scraped . This ideally should be performed at the edge and base of the lesion . These cases should be managed with topical antibiotics [ qid ], atropine drops [ oid ], and systemic NSAIDs if uveitis is suspected . Topical corticosteroids are contraindicated and topical NSAID should be used with great care or not at all . Mechanical debriding could also be performed .
Complicated corneal ulcers are those that do not heal within 72hrs , have a melting stromal component and are infected or unable to heal for some reason . There may be a mechanical obstruction to healing as a result of a foreign body , abrading neoplasia , an indolent ulcer or infection with bacteria or fungi All these also could lead to imminent perforation .
Indolent corneal ulcer : This ulcer classically is a superficial ulcer that shows no healing over at least a two week period . The underlying cause is usually unknown but a previous history of trauma is however
48 • Equine Health Update •